Environmental system for protective suit



1964 R. A. FISCHER ETAL 3,117,426

ENVIRONMENTAL SYSTEM FOR PROTECTIVE SUIT 3 Sheets-Sheet 1 Filed Nov. 25, 1960 INVENTORSI RICHARD A. FISCHER, LAMO/V E. MILLER.

A florney.

5 Sheets-Sheet 2 R. A. FISCHER ETAL ENVIRONMENTAL SYSTEM FOR PROTECTIVE SUIT Jan. 14, 1964 Filed NOV. 25, 1960 INVENTORS." RICHARD A. FISCHER,

A Home LAMON E. MILLER.

8 I Wm, M

Jan. 14, 1964 R. A. FISCHER ETAL 3,117,425

ENVIRONMENTAL SYSTEM FOR PROTECTIVE SUIT Filed Nov. 25, 1960 3 Sheets-Sheet 3 Fig.4.

INVENTORS. RICHARD A. FISCHER, LAMON E. MILLER.

A from ey,

United States Patent This invention relates to an environmental system for use in conjunction with a protective suit designed to protect its user from noxious fumes and vapors, such as may be encountered while fighting fires or handling chemicals.

When a person is exposed to a hostile atmosphere, such as may be encountered when fighting fires or handling chemicals. it is necessary to provide protection against the noxious fumes and vapors that may be encountered. Such protection is normally provided by a protective suit that totally encloses the user. However, it has been found that unless an adequate system of ventilation and cooling is provided within protective suits of this type, the user may be subjected to physical discomfort which can result in fatigue, tension, and possible physical disability.

lt is an object of the present invention to alleviate or remove the above discomforts by providing an independent, self-contained environmental system that may be utilized to supply the occupant of a protective suit of the aforementioned type with a constant flow of cool, dry air taken from a stored supply of liquid air or atmospheric gas for ventilating and cooling purposes.

It is a still further object of the invention to provide an environmental system that can be assembled and worn in a pack, which may be strapped on the users back or incorporated within his protective suit.

One of the difficulties in designing and constructing an environmental system for a protective suit of the aforementioned type is the development of a heat exchanger that will not ice up and render the system ineliicient or inoperative. A prior solution of the problem led to the use of a dual heat exchanger. in the system employing the dual heat exchanger, a valve operated by the temperature within the heat exchanger alternates the flow of liquid air through the heat exchangers in such a way that only one unit will be in use at a time. When the exchanger in use becomes laden with frost, the valve cuts oil the fiow of liquid air through this unit and allows the air to pass through the other exchanger unit.

It is the store another object of the present invention to provide an environmental system having a single heat exchanger and including means for automatically controlling the temperature of the fluid flowing through the heat exchanger in heat exchange relationship to the liquid air to prevent formation of ice therein.

it is still another object of the invention to provide an environmental system of the aforementioned type that provides dehumidiiication of the suit air by removing entrained moisture from the recirculating air at a cold point in the cycle.

Other and further objects of the invention will be apparent from the disclosures in the following specification, appended claims and drawings, wherein:

FIG. 1 is a perspective view of a support pack containing the environmental system for the protective suit;

FIG. 2 is a schematic representation of the environ- Referring to FIG. 2 of the drawings, there is shown a schematic representation of an environmental system designed to provide a flow of cool, dry air to a protective suit 1%, shown in phantom in FIG. 1. The suit forms no part of the subject invention and may be of any type that totally encloses its occupant and affords protection from hostile environments or atmospheres.

The environmental system is adapted to be assembled and contained within a pack container, indicated generally at ll, having a casing 12 adapted either to be strapped on the users back as shown, before he dons the suit, or to be otherwise appropriately secured within the protective suit convenient to the person of the wearer.

The environmental system shown in FIG. 2 includes a cryogenic storage vessel 14 having a double walled cylinder, a fill port 14a and a vent port 14b of conventional design. The storage vessel is provided with a supply of liquid air, liquid oxygen or any liquid, breathable atmospheric gas which is conveyed through a duct 15 to an expansion coil comprising a first pass 16 of a heat exchanger 17, wherein it is vaporized. The vaporized liquid is then used as makeup air in the system in the manner hereinafter described.

Means are provided for circulating air from the suit through a second pass 19 of the heat exchanger 17 in heat exchange relationship to the liquid or vaporized air in the expansion coil in the first pass of the heat exchanger. The means for circulating the suit fluid include a first conduit it? having an open end disposed and arranged to cceive air from the suit through apertures in the casing 12 and conduct it to the second pass 1% of the heat exchanger, and a second conduit 21 arranged to conduct fluid from the second pass 19 of the heat exchanger to an inlet provided in the suit.

An ejector, indicated generally at 23 is disposed in the conduit 2% to inject a regulated flow of the vaporized makeup air from the first pass of the heat exchanger into the suit air ilowing in the conduit. The ejector 23 includes a bellmouth entrance section 24 forming the open end of the conduit 26 and a nozzle joined to outlet of the first pass 16 of the heat exchanger 17 by a duct 26. A valve 28 disposed in the duct 26 is provided with an actuator means 29 arranged to modulate the valve in response to the temperature sensed by a temperature sensing device 30 located in the conduit 2%. The flow of vaporized makeup air through the duct 26 to the nozzle 25 thus may be regulated to automatically control the temperature of the fluid mixture in the conduit 20 at a predetermined temperature to prevent formation of ice in the heat exchanger.

A water and solids trap 32 disposed downstream of the heat exchanger 17 is provided with an opening 33 for admitting water condensed in the conduit 26 and the heat exchanger. A valve 34 is secured to the bottom of the trap for draining the water and contaminates from the trap 32.

To maintain adequate pressure in the storage vessel 14 a portion of the liquid air is diverted from the duct 15' through a duct 35 to a pressure buildup coil 36 and thence back to the top of the vessel 14 where the energy built up by heat absorbed in the coil 36 is utilized to pressurize the liquid air in the storage vessel. A relief valve 33 and a shutoff valve 39 are provided in the duct 35 to prevent excess fluid pressure in the vessel.

In operation, a portion of the warm air in the suit may be discarded through a suitable differential pressure controlled check or dump valve to maintain a desired pressure and prevent an undesirable buildup of carbon dioxide in the suit. This type of valve is well-known in the art and may, for example, comprise a spring loaded check valve ill disposed in the helmet of the suit 10. The valve 49 is shown in phantom view as it forms no part 3 of the invention. The Warm air remaining in the suit flows through the apertures in the casing 12 and is aspirated into the bellmouth entrance 24 of the conduit 21) by the suction generated by the ejector 23. The liquid air from the storage vessel 14 vaporizes in the heat exchanger l7 and flows under pressure to the ejector 23 as cold makeup air. The cold mal up air issues from the ejector nozzle and mixes with the Warm air from the suit to circulate the mixture of warm air and makeup air through the heat exchanger, the water trap, the conduits, and the suit. The makeup air issuing from the ejector nozzle increases the pressure of the circulating mixture to maintain the desired suit pressure and to prevent the entrance of toxic fumes in the event of a tear or leak in the suit.

As the cold makeup air issues from the ejector and mixes with the warm air from the suit, there is a significant decrease in the temperature of the suit air and Water vapor entrained in the air is condensed. Further cooling and water removal are accomplished as the air passes through the heat exchanger l7.

After passing through the heat exchanger, the condensed water and contaminates are collected in the water trap 32 and the cool, dry air mixture is returned through conduit 21 to the suit for distribution over the body skin surface of the suit wearer.

The heat exc. anger 17 serves a two-fold purpose: first it cools the air recirculated from the suit, and second it supplies heat to the liquid air flowing through the first pass of the heat exchanger to help vaporize the liquid air. As noted above, the valve 28 in the duct 26 is modulated in response to the temperature sensed by the temperature sensing device 39 located in the conduit 29, to automatically maintain the temperature of the fluid flowing through the second pass of the heat exchanger at a temperature above the freezing point of the moisture in the air and thereby prevent formation of ice in the heat exchanger.

If desired, additional heat transfer surface may be provided in the first pass of the heat exchanger 1'? by providing extended surfaces or fins on the duct 15 in any suitable, well-known manner.

Referring to FIG. 3 of the drawings there is shown a schematic representation of a modification of the environmental system shown in FIG. 2. The storage vessel and the means for pressurizing the storage vessel in this modified version are the same as shown in FIG. 2 and therefore are omitted from FIG. 3. In this modified version, the duct 15 which conveys liquid air from the storage vessel is first routed to the water trap 32 and is arranged in rows or layers to form a coil fill therein. The outlet of the coil 5%? is connected to the first pass 16 of the heat exchanger 17 and the remainder of the system is the same as shown in FIG. 2.

In operation, the liquid air from the storage vessel is conveyed through the coil 50 in the water trap 32 to the first pass 16 of the heat exchanger 17 Where it vaporizes and flows under pressure to the ejector 23 as cold makeup air. The coil 55 in the water trap serves a two-fold pur pose: first it freezes the condensed water as it collects in the trap 32 so that the pack or system can be placed in any attitude without danger of having Water spill out of the trap, and second it permits partial vaporization of the liquid air before it enters the first pass 15 oi the heat exchanger thereby making it less difficult to prevent ice or frost forming in the heat exchanger. Th peration of the remainder of the modified system shown in FIG. 3 is the same as described for the similar portion of the sys tem in FIG. 2.

Referring to the schematic representation of the modied version shown in FIG. 4, the storage vessel and means for pressurizing the storage vessel are the same as shown in PEG. 2 and therefore are omitted. In the modified version shown in FIG. 4, the duct .5 which conveys liquid air from the storage vessel is routed to the water trap 32 and is arranged in rows or layers to form a coil 52. therein. The outlet of the coil is connected to the duct 26 leading to the ejector 23.

The conduit 24? in this modified version is connected at the end opposite the ejector 23 to one side of the water trap 32, and the duct 21 is arranged to conduct fluid from the opposite side of the trap 32 to an inlet provided in the suit. The valve 23, the actuator means 29, and the temperature sensing device 36 are arranged as shown and described in the system shown in FIG. 2 to control the temperature of the fluid mixture in the conduit 2% at a predetermined temperature. The coil 52 freezes the condensed Water as it collects in the trap 32 and its heat transfer capacity is so chosen as to permit vaporization of the liquid air before it llows through the duct 26, without the necessity of a separate heat exchanger. Thus a considerable saving in Weight and bulk is made possible.

While the invention is described as utilized in an environmental system for a protective suit, it is to be understood that its utility is not limited thereto since it may be utilized in tanks, compartments and many other applications, as will be apparent to those skilled in the art.

We claim:

1. An environmental system for a protective suit adapted to envelope the wearer, comprising: a source of liquid breathable atmospheric gas; a heat exchange means having a first pass comprising an expansion coil communicating with said source of liquid gas; a second pass in said heat exchange means in heat transfer relationship with said expansion coil for vaporizing the liquid gas therein; a first conduit having an open end disposed to receive atmospheric gas from the suit, the other end of said first conduit being connected to the second pass in said heat exchange means; a second conduit connecting the second pass in said heat exchange means to the suit; ejector means operatively connected with said expansion coil and disposed in said first conduit so that atmospheric gas from the suit will be aspirated into the first conduit by the suction generated when vaporized liquid gas is discharged through said ejector means whereby the mixture of vaporized liquid gas and suit atmospheric gas will be circulated over the expansion coil in the heat exchange means and through the second conduit back to the suit; and means operatively associated with said ejector means for automatically controlling the temperature of the gas mixture circulating over the expansion coil.

2. An environmental system for a protective suit adapted to envelope the wearer, comprising: a source of liquid breathable atmospheric gas; a heat exchange means having a first pass comprising an expansion coil communicating with said source of liquid gas; a second pass in said heat exchange means in heat transfer relationship with said expansion coil for vaporizin the liquid gas therein; conduit means arranged to receive atmospheric gas from the suit and conduct it through the second pass of said heat exchange means and back to the suit; and ejector means operatively connected with said expansion coil and disposed in said conduit means upstream of the second pass said heat exchange means so that atmospheric gas from the suit will be aspirated into said conduit means by the suction generated when vaporized liquid gas is discharged through said ejector means i /hereby the mixture of vaporized liquid gas and suit atmospheric gas will be circulated over the expansion coil and ba it to the suit.

3. An environmental system for a protective suit adapted to envelope the wearer, comprising: a source of liquid breathable atmospheric gas; a heat exchange means having a first pass comprising an expansion coil communicating with said source of liquid gas; a second pass in said heat exchange means in heat transfer relationship with said expansion coil for vaporizing the liquid gas therein; a first conduit having an open end disposed to receive atmospheric gas from the suit, the other end of said first conduit being connected to the second pass in said heat exchange means; a second conduit connecting the second pass in said heat exchange means to the suit; ejector means disposed in said first conduit so that atmospheric gas from the suit will be aspirated into the first conduit by the suction generated when vaporized liquid gas is discharged through said ejector means whereby the mixture of vaporized liquid gas and suit atmospheric gas will be circulated over the expansion coil in the heat exchange means and through the second conduit back to the suit; duct means for conducting vaporized liquid gas from the expansion coil in said heat exchange means to said ejector means; valve means in said duct means for controlling the flow of the vaporized liquid gas to said ejector means; and means responsive to the temperature of the gas mixture in said first conduit for modulating said valve means to prevent the temperature of the gas mixture circulating over the expansion coil in said heat exchange means from falling 'below the freezing point of the moisture in the gas.

4. An environmental system for a protective suit adapted to envelope the wearer, comprising: a source of liquid breathable atmospheric gas; a heat exchange means having a first pass comprising an expansion coil communicating with said source of liquid gas; a second pass in said heat exchange means in heat transfer relationship with said expansion coil for vaporizing the liquid gas therein; a first conduit having an open end disposed to receive atmospheric gas vfrom the suit, the other end of said first conduit being connected to the second pass in said heat exchange means; a second conduit connecting in the second pass in said heat exchange means to the suit; ejector means disposed in said first conduit so that atmospheric gas from the suit will be aspirated into the first conduit by the suction generated when vaporized liquid gas is discharged through said ejector means whereby the mixture of vaporized liquid gas and suit atmospheric gas will be circulated over the expansion coil in the heat exchange means and through the second conduit back to the suit; duct means for conducting vaporized liquid gas from the expansion coil in said heat exchange means to said ejector means; valve means in said duct means for controlling the flow of the vaporized 'liquid gas to said ejector means; means responsive to the temperature of the gas mixture in said first conduit for modulating said valve means to prevent the temperature of the gas mixture circulating over the expansion coil in said heat exchange means from falling below the freezing point of the moisture in the gas; and means associated with said heat exchange means for collecting moisture condensed in said first conduit and said heat exchange means.

5. An environmental system for a protective suit adapted to envelope the wearer, comprising: a container for storing and supplying liquid breathable atmospheric gas; means for pressurizing said container; a heat exchange means having. a first pass comprising an expansion coil communicating with said container; a second pass disposed in said heat exchange means in heat transfer relationship with said expansion coil for vaporizing the liquid gas therein; conduit means arranged to receive atmospheric gas from the suit and conduct it through the second pass of said heat exchange means and back to the suit; and ejector means operatively connected with said expansion coil and disposed in said conduit means upstream of the second pass in said heat exchange means so that atmospheric gas from the suit will be aspirated into said conduit means by the suction generated when vaporized liquid gas is discharged through said ejector means whereby the mixture of vaporized liquid gas and suit atmospheric gas will be circulated over the expansion coil and back to the suit.

6. An environmental system for a protective suit adapted to envelope the wearer, comprising: a container for storing and supplying liquid breathable atmospheric gas; means for pressurizing said container; a heat exchange means having a first pass comprising an expansion coil communicating with said container; a second pass disposed in said heat exchange means in heat transfer relationship with said expansion coil hor vaporizing the liquid gas therein; conduit means arranged to receive atmospheric gas from the suit and conduct it through the sec ond pass of said heat exchange means and back to the suit; ejector means operatively connected with said expansion coil and disposed in said conduit means upstream of the second pass in said heat exchange means so that atmospheric gas from the suit will be aspirated into said conduit means by the suction generated when vaporized liquid gas is discharged through said ejector means whereby the mixture of vaporized liquid gas and suit atmospheric gas will be circulated over the expansion coil and back to the suit; and means operatively associ ated with said ejector means for controlling the temperature of the mixture of suit atmospheric gas and vaporized liquid gas flowing over the expansion coil in said heat exchange means to prevent the temperature of the gas mixture from falling below the freezing point of the moisture in the mixture.

7. An environmental system for a protective suit adapted to envelope the wearer, comprising: a container for storing and supplying liquid breathable atmospheric gas; means for pressurizing said container; a heat exchange means having a first pass comprising an expansion coil communicating with said container; a second pass disposed in said heat exchange means in heat transfer relationship with said expansion coil for vaporizing the liquid gas therein; conduit means arranged to receive atmospheric gas from the suit and conduct it through the second pass of said heat exchange means and back to the suit; ejector means operatively connected with said expansion coil and disposed in said conduit means upstream of the second pass in said heat exchange means so that atmospheric gas from the suit will be aspirated into said conduit means by the suction generated when vaporized liquid gas is discharged through said ejector means whereby the mixture of vaporized liquid gas and suit atmospheric gas will be circulated over the expansion coil and back to the suit; means operatively associted with said ejector means for controlling the temperature of the mixture of suit atmospheric gas and vaporized liquid gas flowing over the expansion coil in said heat exchange means to prevent the temperature of the gas mixture from falling below the freezing point of the moisture in the mixture; and means associated with said heat exchange means for collecting moisture condensed in said heat exchange means.

8. An environmental system for a protective suit adapted to envelope the wearer, comprising: a source of liquid breathable atmospheric gas; a heat exchange means having a first pass comprising an expansion coil; duct means connecting said source ofv liquid atmospheric gas with said expansion coil; a second pass in said heat ex change means disposed in heat transfer relationship with said expansion coil for vaporizing the liquid gas therein; means for circulating atmospheric gas from the suit through the second pass of said heat exchange means and back to the suit, said circulating means including an ejector operatively connected to the expansion coil and disposed in said circulating means so that the fluid flowing through the second pass of said heat exchange means in heat transfer relationship to the expansion coil comprises a mixture of vaporized liquid gas from the expansion coil and atmospheric gas from the suit; means for collecting moisture condensed in said circulating means, said duct means having a portion disposed in said collecting means; and means operatively associated with said ejector for automatically controlling the temperature of the gas mixture flowing over the expansion coil in the second pass of said heat exchange means.

9. An environmental system for an enclosure having means for venting fluid from the enclosure, comprising: a source of liquid breathable atmospheric gas; a heat exchange means having a first pass comprising an expansion coil communicating with said source of liquid gasya second pass in said heat exchange means in heat transfer suction generated when vaporized gas is discharged through said ejector means whereby a mixture of vaporized liquid gas from said expansion coil and atmospheric gas from said source will flow through the second pass in said heat exchange means in heat transfer relationship with said expansion coil and through the second conduit to the enclosure; and means operatively associated with said ejector means for automatically controlling the temperature of the gas mixture flowing over the expansion coil in the second pass in said heat exchanger means.

l0. An environmental system for an enclosure having means for venting fluid from the enclosure, comprising: a container for storing and supplying liquid breathable atmospheric gas; means for pressurizing said container; a heat exchange means having a first pass comprising an expansion coil communicating with said container; a second pass in said heat exchang v lationship with said expansion coil for vaporizing the liquid gas therein; conduit meahsfor conducting atr'nospheric gas from a source to the second pass of said heat exchange means and from the second pass to the enclosure; ejector means operatively connected with the expansion coil and disposed in said conduit means upstream of the second pass of said heat exchange means so that atmospheric gas from said source will be aspirated into the con duit means by the suction generated when vaporized gas is discharged through said ejector means whereby a mixture of vaporized liquid gas from said expansion coil and atmospheric gas from said source will flow through the second pass in said heat exchange means in heat transfer relationship with said expansion coil and thence to the enclosure; and means operatively associated with said ejector means for controlling the temperature of the mixture of atmospheric gas and vaporized liquid gas flowing through the second pass in said heat exchange means to prevent the temperature of the gas mixture from falling below the freezing point of the moisture in the mixture.

References flitcd in the file of this patent UNITED STATES PATENTS Leflingwell July 4, 1961 3,064,448 Whittington Nov. 20, 1962 means in heat transfer re-. 

1. AN ENVIRONMENTAL SYSTEM FOR A PROTECTIVE SUIT ADAPTED TO ENVELOPE THE WEARER, COMPRISING: A SOURCE OF LIQUID BREATHABLE ATMOSPHERIC GAS; A HEAT EXCHANGE MEANS HAVING A FIRST PASS COMPRISING AN EXPANSION COIL COMMUNICATING WITH SAID SOURCE OF LIQUID GAS; A SECOND PASS IN SAID HEAT EXCHANGE MEANS IN HEAT TRANSFER RELATIONSHIP WITH SAID EXPANSION COIL FOR VAPORIZING THE LIQUID GAS THEREIN; A FIRST CONDUIT HAVING AN OPEN END DISPOSED TO RECEIVE ATMOSPHERIC GAS FROM THE SUIT, THE OTHER END OF SAID FIRST CONDUIT BEING CONNECTED TO THE SECOND PASS IN SAID HEAT EXCHANGE MEANS; A SECOND CONDUIT CONNECTING THE SECOND PASS IN SAID HEAT EXCHANGE MEANS TO THE SUIT; EJECTOR MEANS OPERATIVELY CONNECTED WITH SAID EXPANSION COIL AND DISPOSED IN SAID FIRST CONDUIT SO THAT ATMOSPHERIC GAS FROM THE SUIT WILL BE ASPIRATED INTO THE FIRST CONDUIT BY THE SUCTION GENERATED WHEN VAPORIZED LIQUID GAS IS DISCHARGED THROUGH SAID EJECTOR MEANS WHEREBY THE MIX- 